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Basic Wiring Diagram. Objectives. Gain a better understanding of the basic concept of reading and navigating wiring diagrams Review different types of wiring diagrams Review of common symbols How to navigate a wiring diagram efficiently. Two basic types of Wiring Diagrams.
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Basic Wiring Diagram Objectives • Gain a better understanding of the basic concept of reading and navigating wiring diagrams • Review different types of wiring diagrams • Review of common symbols • How to navigate a wiring diagram efficiently
Two basic types of Wiring Diagrams Ladder Diagrams: Easy to navigate, Line by Line illustrations. Legend offer part description and line numbers. Easier to determine unit operation. Schematic Diagrams (Pictorial): Harder to navigate. Each component will need to be traced. European Diagrams: Difficult to navigate. with components Drawings may be several pages.
Schematic (Pictorial) Example Notice how each Component is spread Out Components and wires can be shown in exact locations. Wires and components will need to be traced to determine unit operation
Ladder Example The ladder diagram displays a complete electrical circuit. Easier understanding of unit operation. Left side indicates the Line side of the circuit while the right side indicates the Neutral side. Loads are shown between control voltage lines
European Example; First drawing contains the legend Component labeling indicates page and line location of the other portions of that component Line and control voltage lines are located on the top and bottom of the pages
Common Symbols Note; a single device may have different symbols depending On the manufacturer drawings.
Component Diagram Component layout diagrams are often found with wiring diagrams So you can physically locate where each device in the wiring diagram is mounted in the control panel.
How do you read a Wiring Diagram • Keep it Simple Stupid (KISS) • Break your diagram down to just the section you need • Use your legend to identify each device (don’t assume!) • Take notes as you go, draw out the diagram on a separate piece of • paper. This will help you to see the complete circuit without the • confusion from other pieces of the puzzle. • Start at the source of your problem and work your way backwards. Many times the unit manual will break out a single piece of a diagram for you. Use your resources!!!
Example 1 You discover that Outdoor Fan Motor #1 Is not running. What is your next step? Do we need to review The entire diagram? How do we locate Outdoor Fan Motor#1 On a schematic type Diagram? Can we break the Diagram down to make It easier to read?
Example 1 Use your legend to determine the outdoor fan motor abbreviation.
Example 1 Once you determine the abbreviation of the outdoor fan motor, isolate this portion of the diagram . You may need to other portion of the diagram later to further diagnose.
Example 1 If the unit is equipped with a component diagram, use the drawing to determine the physically locate the individual components.
Example 1 Outdoor Fan Motor not running: What is your next step? PrimaryVoltage Replace Fuses No Yes Fan Contactor Trace Wires Feeding Contactor No Yes Secondary Voltage Trace Wires Feeding Low Voltage Where is my low voltage? No Yes Test Voltage at Motor Trace Wires Feeding Line Voltage No Yes Test Motor
Example 2 How do we find an object on a ladder diagram? Each device is represented by a designation as shown here in the legend. The last column shows the line number/s associated with each device Take note of 1K4 What line number it can be found on the drawing.
Example 2 We noted from the legend that 1K4 represents the blower relay. What lines can we find the blower relay on? If you look at your ladder diagram you will notice a set of numbers going down one side. 1K4 is referenced as being on line 13 in the legend. See below to match up 1K4 on line number 13.
Example 2 The numbering found next to the right hand line indicates the contact line location of the load device found inside the schematic.
Example 3 Installing a Fan Terminal controller on a PIU In order to make the outputs of the controller work you must add a jumper to each of the outputs to complete the low voltage circuit. Steps 1: Determine the how the factory wiring is configured by Reading the wiring diagram supplied with the unit, start by tracing Out the fan relay coil. Leave the manufactured literature with the device when finished. Step 2: Next Trace out the Heat stage 1 contactor coil Step 3: Trace out the Heat stage 2 contactor coil Step 4: Place the necessary jumpers on your controller
Common – What is a common in a wiring diagram? The term common, can be misused… The term common means just that. Common to something. In electricity, it can mean common to ground (which is a neutral leg of an electrical circuit, or it can mean common to another terminal or wire (as in a relay or contactor). Different manufacturer’s use different terminology so it is important to pay attention to your diagram to ensure you are reading your “common” points as to which common the diagram is referring to.
Example 4 Defining Common in a diagram Question 1: Why is the C Terminal located next to the H1 and H2 Terminals? Question 2: What does that indicate? Question 3: Why is there no Fan Terminal to connect to? Question 4: Why is there a ground symbol connected to the C Terminal block? Question 5: What does that mean?
Example 5 Breaking down the circuit You receive a work order that states the Space Temperature reading on a Package RTU is off by 25 DF. Upon arrival you find a diagram for the space temperature sensors being used to average the space temp over a large area. Question 1: What do you notice about this diagram? Question 2: What is representing each sensor in the group? Question 3: What happens when you wire a resistor in parrallel With another resistor? Question 4: What happens when you wire a resistor in series With another resistor? Question 5: What can you do to make troubleshooting easier?
Example 6 What is wrong with this diagram? Question 1: What does every electrical circuit need to be complete? Question 2: Notice that the Discrete output is wired to the output, But what about the common? Question 3: Is the common on the controller output terminal block Common to ground or common to the outputs? Keep in mind, these diagrams are man made, never Assume anything. Use your resources.